Gallium nitride particles and methods for producing the same

Abstract

Provided are high-purity gallium nitride particles with low oxygen content, suitable for use in raw materials and sintered bodies. The particles are characterized by an oxygen content of 0.5 atomic percent or less and a total impurity content of less than 10 wtppm of elements including Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd.

Description

Technical Field

[0001] The present invention relates to gallium nitride particles used as a raw material for a gallium nitride sintered body used in producing a gallium nitride thin film by a sputtering method. Background Art

[0002] Gallium nitride has attracted much attention as a raw material for the light-emitting layer of blue light-emitting diodes (LEDs) and blue laser diodes (LDs). In recent years, it has been used in the form of thin films and substrates for various applications such as white LEDs and blue LDs. In the future, it will also attract attention as a material for power devices and other applications.

[0003] As a method for producing a thin film of gallium nitride, a sputtering method using a target material can be cited. A sputtering target of gallium nitride is produced by molding or sintering gallium nitride powder. However, if the gallium nitride powder used as the raw material of the target material has a high oxygen content, a gallium nitride film containing a large amount of oxygen will be formed, resulting in problems such as reduced crystallinity. In addition, to date, if the amount of oxygen is to be reduced, the particle size will become larger. In particular, when a sintered body exceeding 120 mm is to be obtained, there are problems such as insufficient strength and inability to maintain the shape. In addition, when used in various devices, in order to control the amount of various dopants, the gallium nitride sputtering target used as the raw material is required to be of high purity, but to date, it has not been possible to produce such a sintered body.

[0004] A commonly known method for producing gallium nitride powder involves heating metallic gallium to a temperature between 1000°C and 1200°C in an ammonia gas stream to produce polycrystalline gallium nitride. This method forms gallium nitride on the surface of the gallium metal, hindering contact between the gallium metal and the ammonia gas within, preventing further nitridation. Furthermore, metallic gallium has a low melting point of approximately 30°C, so it becomes liquid during the nitridation process, leaving a limited surface area for reaction and hindering the reaction.

[0005] Another method involves heating gallium oxide in an ammonia atmosphere to produce gallium nitride (see, for example, Patent Documents 1 and 2). While the resulting substance is identified as gallium nitride by fluorescent X-rays and electron probe microanalyzer (EPMA), there is no description of the trace impurities in the powder, nor is there any detailed description of the ammonia atmosphere.

[0006] Furthermore, although there are other methods for obtaining gallium nitride powder (see, for example, Patent Document 3), it is difficult to obtain a powder having an oxygen content below a predetermined level using this technology.

[0007] Patent Document 4 discloses a technology in which gallium oxide is vaporized in a reducing atmosphere to obtain Ga2O gas, and the obtained Ga2O gas is nitrided to obtain gallium nitride powder. However, the gallium source gas contains a large amount of oxygen, and it is impossible to obtain a powder that has both low oxygen content and high purity.

[0008] Patent Document 5 discloses a technique related to gallium nitride particles with a low oxygen content. However, since the particles are not precipitated after being vaporized, a high-purity powder cannot be obtained.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-29713

[0012] Patent Document 2: Japanese Patent Application Laid-Open No. 2000-198978

[0013] Patent Document 3: Japanese Patent Application Laid-Open No. 2013-129568

[0014] Patent Document 4: Japanese Patent Application Laid-Open No. 2009-234800

[0015] Patent Document 5: International Publication No. 2018-230663 Summary of the Invention

[0016] Problems to be solved by the invention

[0017] An object of the present invention is to provide a sputtering target capable of producing low-oxygen, high-density, high-purity gallium nitride, and gallium nitride particles having a low oxygen content and low impurities in a gallium nitride single crystal.

[0018] Solutions for solving problems

[0019] In view of this background, the present inventors conducted intensive research and, as a result, studied nitridation conditions and discovered conditions for obtaining high-purity gallium nitride particles with a low oxygen content, thereby completing the present invention.

[0020] That is, the present invention has the following gist.

[0021] (1) A gallium nitride particle characterized in that the oxygen content is less than 0.5 atomic % and the total impurity amount of elements such as Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is less than 10 wtppm.

[0022] (2) The gallium nitride particles according to (1), characterized in that the total impurity amount of Mg and Si is less than 5 wtppm.

[0023] (3) The gallium nitride particles according to (1) or (2), characterized in that the Si impurity amount is less than 1 wtppm.

[0024] (4) The gallium nitride particles according to any one of (1) to (3), wherein the oxygen content is 0.1 atomic % or less.

[0025] (5) A method for producing gallium nitride particles according to any one of (1) to (4), characterized in that, after gallium oxide is subjected to nitridation treatment as a starting material, transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the gallium oxide subjected to nitridation treatment heated to 1150°C to 1300°C as a precipitation treatment, and precipitation ammonia gas heated to 900°C to 1100°C is introduced into the vaporized gallium nitride to cause precipitation, thereby obtaining gallium nitride particles.

[0026] (6) A sintered body comprising the gallium nitride particles according to any one of (1) to (4).

[0027] (7) A sputtering target material obtained by using the sintered body described in (6).

[0028] (8) A thin film formed using the sputtering target described in (7).

[0029] Effects of the Invention

[0030] By using the gallium nitride particles of the present invention, high-purity gallium nitride targets with low oxygen content can be produced, enabling the formation of gallium nitride thin films with good crystallinity. Furthermore, they can also be used as raw materials for gallium nitride single crystals produced by non-thermal methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an example of an apparatus for producing gallium nitride particles of the present invention.

[0032] Figure 2 This is an example of an apparatus for producing gallium nitride particles of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0034] The gallium nitride particles of the present invention are characterized by having an oxygen content of 0.5 atomic % or less, preferably 0.2 atomic % or less, and more preferably 0.1 atomic % or less. This can reduce the oxygen content in the gallium nitride sintered body after sintering.

[0035] The gallium nitride particles of the present invention are characterized by having a total impurity content of less than 10 wtppm of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd. These elements are contained in the p-type and n-type semiconductors that form gallium nitride and, in order to control their inclusion, must not be present in the gallium nitride particles used as the raw material. The total impurity content is preferably 5 wtppm or less, more preferably 3 wtppm or less, even more preferably 1 ppm or less, and even more preferably 0.5 ppm or less.

[0036] Among these impurities, the total amount of Mg and Si, which have high activation rates, is preferably 5 wtppm or less, more preferably 2 wtppm or less, further preferably 1 wtppm or less, and further preferably 0.5 ppm or less. The amount of Si impurities is further preferably 1 wtppm or less, further preferably 0.5 ppm or less.

[0037] The gallium nitride particles of the present invention preferably have a primary particle size of 50% of approximately spherical gallium nitride particles of 5 μm or less, more preferably 3 μm or less. This allows the approximately spherical gallium nitride particles to fully exhibit the effects of low oxygen and high sinterability.

[0038] The gallium nitride particles of the present invention preferably have an average particle size of 20 μm or less, more preferably 1 μm to 20 μm or less, 1 μm to 10 μm or less, and particularly preferably 1 μm to 8 μm or less.

[0039] In addition, the 50% particle size of the primary particles of the gallium nitride particles of the present invention is preferably 5 μm or more and 50 μm or less, preferably 7 μm or more and 40 μm or less, and further preferably 10 μm or more and 30 μm or less. By making the particle size 5 μm or more, the influence of surface oxidation can be reduced, the amount of oxygen can be reduced, and the density during sintering can be improved. In addition, the decomposition at high temperatures that may usually occur due to the small surface layer can be suppressed to some extent, and the calcination temperature can be increased. By setting the particle size to 50 μm or less, the surface is larger and sintering is easily promoted. The particle size here refers to the 50% particle size in the area of ​​the primary particles observed under a scanning electron microscope, etc.

[0040] The gallium nitride of the present invention preferably has a plate-like shape for large-diameter particles. This is because, unlike crystal growth originating from a conventional substrate, growth originating from particles primarily results in lateral plate-like growth, rather than growth along the c-axis like columns. Ultimately, the particles are sintered into a plate-like shape, making plate-like shapes preferable to columnar shapes.

[0041] The bulk density is preferably greater than 1.2 g / cm 3 , more preferably greater than 1.4g / cm3 , more preferably greater than 1.6 g / cm 3 This improves the filling property and facilitates densification during firing. When used as a raw material for a single crystal, the occupied volume can be reduced, making it possible to downsize the container.

[0042] Next, the method for producing gallium nitride particles of the present invention will be described.

[0043] The method for producing gallium nitride particles of the present invention involves the following method: after gallium oxide is subjected to a nitriding treatment as a starting material, a transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the gallium oxide that has been nitrided to a temperature of 1150°C to 1300°C as a precipitation treatment, and a precipitation ammonia gas heated to a temperature of 900°C to 1100°C is introduced into the vaporized gallium nitride to precipitate the gallium nitride, thereby obtaining gallium nitride particles.

[0044] The purity of gallium oxide used in the present invention is preferably 4N (99.99%) or higher, more preferably 5N (99.999%) or higher. By increasing the purity of gallium oxide used, high-purity gallium nitride particles can be obtained.

[0045] The nitriding temperature of gallium oxide during nitriding is preferably 1000° C. to 1100° C., more preferably 1025° C. to 1075° C. By performing the treatment within this range, gallium oxide can be nitrided and gasification can be suppressed.

[0046] To achieve complete nitridation, the treatment time during the nitridation treatment is preferably 3 hours or longer, more preferably 6 hours or longer. Since decomposition does not progress significantly at these nitridation treatment temperatures, the yield does not change significantly. However, from the perspective of achieving a balance between productivity and nitridation effect, the treatment time is preferably within 60 hours.

[0047] Regarding the flow rate of ammonia gas during the nitriding treatment, in order to promote nitriding and prevent decomposition into gallium during the nitriding treatment, the molar ratio of nitrogen in the ammonia gas / gallium in the gallium oxide is preferably 5 or more, more preferably 10 or more. Furthermore, by setting the ammonia gas flow rate during the nitriding treatment within the above range, with the amount of ammonia gas reacted per unit time preferably being 1 times the molar amount of the gallium fed, more preferably being 1.5 times the molar amount, and particularly preferably being 2 times the molar amount, the gasification reaction of gallium oxide and the decomposition reaction of the synthesized gallium nitride can be suppressed.

[0048] After the nitriding treatment, ammonia gas for transport, heated to a temperature of 1150°C to 1300°C, is introduced into the gallium oxide, which has been nitrided, as a precipitation treatment. The temperature of the ammonia gas for transport is preferably 1150°C to 1200°C. By treating within this range, highly purified vaporized gallium nitride particles can be obtained without decomposing into nitrogen and gallium. Without the use of ammonia gas for transport, gallium nitride decomposes into nitrogen and gallium, preventing the desired substance from being obtained.

[0049] The time for introducing the transport ammonia gas into the gallium oxide that has been nitrided and heated to a temperature between 1150°C and 1300°C is preferably 3 hours or longer, more preferably 6 hours or longer. If the time is shorter than this, the amount of precipitation is small, the yield is low, and grain growth does not proceed. Oxidation of the particle surface during removal progresses, making it difficult to obtain gallium nitride particles with the desired oxygen content. The upper limit is preferably 30 hours or shorter, more preferably 20 hours or shorter. If the time is longer than this, the grains grow significantly, and the particles are not suitable for the intended use.

[0050] As a precipitation treatment, transport ammonia gas is introduced into the nitrided gallium oxide. Then, precipitation ammonia gas heated to between 900°C and 1100°C is introduced into the vaporized gallium nitride for precipitation. The introduction of precipitation ammonia gas allows the vaporized gallium nitride particles to precipitate. Importantly, the use of ammonia for precipitation is crucial. Simply lowering the furnace temperature results in preferential precipitation on the furnace walls, resulting in a high concentration of impurities derived from the furnace's materials. Furthermore, without the presence of reactive gases such as ammonia during precipitation, metallic gallium and gallium oxide will precipitate due to insufficient nitrogen. Furthermore, the ammonia gas used for precipitation must be sprayed onto the precipitation site within 30 seconds of reaching the specified temperature. Prolonged exposure to temperatures above 1000°C causes ammonia gas to separate into nitrogen and hydrogen, preventing the production of active species (such as NH2) required for reaction with gallium, and thus hindering the precipitation reaction. Furthermore, at low temperatures, the particles become finer, making it difficult to maintain oxygen levels.

[0051] By setting the temperature of the ammonia gas used for precipitation to the above range, grain growth can be carried out without re-decomposition. In this way, by gasifying the gallium nitride particles and then precipitating and growing the grains, the purity of the gallium nitride particles can be improved. Furthermore, in order to improve the purity, it is preferred that there is no substrate, seed crystal, etc. for the gallium nitride particles at the precipitation site. If there is a substrate, seed crystal, etc., oxygen and impurities derived from these will be mixed in, making it difficult to obtain high-purity gallium nitride particles. In addition, when growing on a substrate, it will not grow in a granular form, so post-processing such as crushing is required, which becomes a cause of impurity mixing. The loose density of the particles precipitated in this way becomes larger, making it a material useful as a material for the production of sintered bodies and single crystal synthesis.

[0052] The position where the gasified gallium nitride particles are deposited is based on the inlet of the ammonia gas and can therefore be freely set. An example of the introduction method is shown in FIG. Figure 1 .

[0053] The precipitation treatment time is preferably 3 hours or longer, more preferably 6 hours or longer. If the treatment time is shorter, the precipitation amount is small, the yield is low, and grain growth does not progress. Oxidation of the particle surface during extraction progresses, making it difficult to obtain gallium nitride particles with the desired oxygen content. The upper limit is preferably 30 hours or shorter, more preferably 20 hours or shorter. If the treatment time exceeds this, the grains grow significantly, making the particles unsuitable for the intended purpose.

[0054] The temperature of the ammonia gas used to precipitate the vaporized gallium nitride is within the temperature range in which gallium nitride particles can precipitate, i.e., between 900°C and 1100°C, preferably between 1000°C and 1100°C. By introducing the ammonia gas at this temperature range, the vaporized gallium nitride particles are cooled and precipitated in the ammonia gas. Furthermore, the precipitated gallium nitride particles can grow to a constant particle size. The amount of ammonia gas used at this time is preferably such that the molar ratio of nitrogen in the ammonia gas to gallium in the container, measured at a flow rate per hour, is at least 1, more preferably at least 2, and particularly preferably at least 3.

[0055] The outermost surface of the particles thus precipitated can be decomposed to precipitate metallic gallium. The precipitation of metallic gallium gives the particle surface a curved surface and also inhibits oxidation from the outermost surface. As a result, the color becomes close to gray.

[0056] To remove water generated during the nitriding treatment, it is preferable to maintain the temperature for several hours below the temperature of the nitriding treatment between the nitriding treatment step and the step of introducing ammonia gas into the nitrided gallium oxide.

[0057] The gallium nitride particles of the present invention have a low oxygen content, and therefore, a sintered body with a low oxygen content can be formed. The sintered body can be obtained, for example, by subjecting the gallium nitride particles of the present invention to a hot pressing treatment at a temperature of 1060°C or higher and lower than 1200°C. The hot pressing method is a device that promotes sintering by applying pressure to the powder while providing temperature. Since the hot pressing method is a sintering method that assists the diffusion of elements in the treated object during sintering by uniaxial pressing during heating, even materials that are difficult to sinter can be sintered in the case of containing elements with a low diffusion coefficient or when treating powders with large particle sizes. By sintering by hot pressing, the density is improved compared to the past, and for example, a material with a density of 3.0 g / cm 3 Above high density sintered body.

[0058] The sintered body containing the gallium nitride particles of the present invention has a low oxygen content, and therefore, a sputtering target with a low oxygen content can be formed. The sputtering target can be obtained by fixing (bonding) it to a flat or cylindrical support by an adhesive such as a solder material. The material of the support is not particularly limited as long as it has high thermal conductivity and strength to support the molded object. For reasons of high thermal conductivity and strength, metals such as Cu, SUS or Ti are preferred. As for the shape of the support, a flat-plate-shaped molded object uses a flat-plate-shaped support, and a cylindrical-shaped molded object uses a cylindrical-shaped support. The adhesive material (adhesive material) used to bond the molded object to the support is not particularly limited as long as it has sufficient bonding strength to support it. Conductive resins, tin-based solder materials or indium-based solder materials can be used. Indium solder is preferred because of its high electrical conductivity and thermal conductivity, and because it is soft and easily deformed.

[0059] A sputtering target formed using a sintered body containing the gallium nitride particles of the present invention has a low oxygen content and can therefore form a gallium nitride thin film with good crystallinity.

[0060] Example

[0061] The present invention will be specifically described using the following examples, but the present invention is not limited to these examples.

[0062] (Determination of oxygen content of particles)

[0063] The object was thermally decomposed and the oxygen content was measured by the thermal conductivity method using an oxygen / nitrogen / hydrogen analyzer (manufactured by Leco). The calculated value is weight %, so

[0064] Oxygen amount (atomic %) = (oxygen amount (weight %) / oxygen atomic weight) / ((nitrogen amount (weight %) / nitrogen atomic weight) + (gallium amount (weight %) / gallium atomic weight) + (oxygen amount (weight %) / oxygen atomic weight))

[0065] The nitrogen content (weight %) and the gallium content (weight %) were measured using an oxygen / nitrogen / hydrogen analyzer (manufactured by Leco Corporation), and the remainder of oxygen and nitrogen was calculated using gallium.

[0066] (50% particle size)

[0067] The 50% particle size of primary particles is determined as follows: Using an SEM, first observe at 50x magnification to determine the presence, diameter, and area of ​​particles exceeding 100 μm. Next, at 200x magnification, determine the presence, diameter, and area of ​​particles between 10 and 100 μm. Next, at 1000x magnification, determine the presence, diameter, and area of ​​particles between 5 and 10 μm. Finally, at 5000x magnification, determine the presence, diameter, and area of ​​particles below 5 μm. At least three images of each are taken and combined to form the overall particle size distribution. Particles are calculated as those without observed grain boundaries. Even if aggregated, particles with grain boundaries are counted as distinct particles. The diameter of the particle with the 50% cumulative area ratio is defined as the 50% primary particle size.

[0068] (Average particle size)

[0069] The average particle size is determined as follows: Using an SEM, first observe at 50x magnification to determine the presence and diameter of particles larger than 100 μm. Then, at 200x magnification, determine the presence and diameter of particles between 10 and 100 μm. Then, at 1000x magnification, determine the presence and diameter of particles between 5 and 10 μm. Finally, at 5000x magnification, determine the presence and diameter of particles less than 5 μm. Measure at least three of each of these images and combine them to form the overall particle size distribution. Particles are calculated as particles without observed grain boundaries. Even if aggregated, particles with grain boundaries are calculated as distinct particles. The arithmetic mean diameter of these particles is taken as the average particle size.

[0070] (Molar ratio of ammonia to gallium)

[0071] The ratio is calculated based on the molar number of gallium in the input gallium oxide or gallium nitride particles, the flow rate, and the flow time, and the molar number of ammonia (volume conversion at 25° C.).

[0072] (Amount of ammonia (NH3) reaction per unit time)

[0073] The amount of ammonia reacted per unit time was calculated as (ammonia / gallium molar ratio) / reaction holding time.

[0074] (Bulk density)

[0075] The bulk density of gallium nitride particles is measured in accordance with JIS Z2504.

[0076] (Determination of the amount of impurities in particles)

[0077] Impurities in the particles were analyzed by GDMS (glow discharge mass spectrometry).

[0078] Examples 1 to 3

[0079] Device Usage Figure 140 g of gallium oxide powder (5N: needle-shaped) was weighed and placed in an alumina container. Figure 1 The nitriding treatment was performed on the portion of container 2 of tubular furnace 1. After the furnace was purged with vacuum, ammonia gas was filled and 1000 mL / min of ammonia gas for nitriding treatment was introduced from pipe 10. The temperature of container 2 was increased at 10°C / min to 1050°C and maintained for 18 hours (ammonia / gallium molar ratio = 103.5). After temporarily cooling to below 200°C, as a precipitation treatment, 1000 mL / min of ammonia gas for transport was introduced from pipe 10, and the temperature was raised at 10°C / min. The ammonia gas for introduction was introduced into the gallium oxide that had been nitrided and heated to 1150°C, vaporizing the gallium nitride. The vaporized gallium nitride was then partially heated to 1150°C. After this, as precipitation ammonia gas, the ammonia gas for precipitation was heated to 1000°C and introduced from pipe 20 at 1000 ml / min. This was maintained for 1 hour, 6 hours, or 12 hours (ammonia gas / molar ratio at time of introduction: 1-hour treatment: 5.75, 6-hour treatment: 34.5, 12-hour treatment: 69). The gallium nitride particles precipitated directly above container 2 were recovered, and the yield and various physical properties were confirmed. The physical properties of the resulting gallium nitride particles are shown in Tables 2 and 3.

[0080] Example 4

[0081] Device Usage Figure 2 40 g of gallium oxide powder (5N: needle-shaped) was weighed and placed in an alumina container. Figure 2 Nitriding treatment was performed in section 2 of tubular furnace 1. After the furnace was purged with vacuum, ammonia gas was filled in. 1000 mL / min of ammonia gas for nitriding treatment was introduced from pipe 10. The temperature of vessel 2 was raised at 10°C / min, ultimately to 1050°C, where it was maintained for 18 hours (ammonia / gallium molar ratio = 103.5). The temperature was temporarily lowered to below 200°C. Then, as a precipitation treatment, 500 mL / min of ammonia gas for transport was introduced from pipe 10. The temperature was raised at 10°C / min. This ammonia gas for transport was introduced into the gallium oxide, which had been nitrided and heated to 1150°C, vaporizing the gallium nitride. The vaporized gallium nitride was then heated to 1150°C in section 3. After this, ammonia gas for precipitation was heated to 1000°C and introduced from pipe 20 at 1000 mL / min, where it was maintained for 6 hours (ammonia / gallium molar ratio at the time of introduction: 34.5, for the 6-hour treatment). The particles precipitated in the container 3 were recovered, and the yield and various physical properties were confirmed. Table 2 shows the physical property values ​​and yield of the obtained gallium nitride particles.

[0082] Example 5

[0083] Device Usage Figure 140 g of gallium oxide powder (5N: needle-shaped) was weighed and placed in an alumina container. Figure 1 The nitriding treatment was performed in container 2 of tubular furnace 1. After the furnace was purged with vacuum, ammonia gas was filled and introduced from pipe 10 at a rate of 1000 mL / min for nitriding treatment. The temperature of container 2 was raised at 10°C / min to 1050°C and maintained for 18 hours. Without cooling, as a precipitation treatment, 1000 mL / min of ammonia gas for transport was introduced from pipe 10 at a rate of 10°C / min, and the temperature was raised at 10°C / min. This ammonia gas for introduction was introduced into the gallium oxide that had been nitrided and heated to 1150°C, vaporizing the gallium nitride. The vaporized gallium nitride was then heated to 1150°C in container 2. Subsequently, ammonia gas for precipitation was heated to 1050°C and introduced from pipe 20 at a rate of 1000 mL / min for 6 hours (molar ratio of ammonia gas to gallium at the time of introduction: 34.5 for the 6-hour treatment). The gallium nitride particles deposited just above the container 2 were recovered, and the yield and various physical properties were confirmed. The physical property values ​​of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0084] Comparative Example 1

[0085] use Figure 1 Gallium oxide treatment was performed in the same manner as in Examples 1 to 3, except that the temperature of the vessel during the precipitation treatment and during the introduction of the transport ammonia gas was maintained at 1200°C, and ammonia gas was introduced from pipe 10 at a rate of 1000 ml / min, without using pipe 20. In this case, since no ammonia gas for precipitation was used, no gallium nitride particles remained in vessel 2. Gallium nitride particles precipitated around the furnace core tube at the outlet of the tubular furnace were obtained. However, due to their small average particle size and precipitation within the furnace core tube, the oxygen content and purity were low, and the desired product could not be obtained. The physical properties of the resulting gallium nitride particles are shown in Tables 2 and 3.

[0086] Comparative Example 2

[0087] Gallium oxide was treated in the same manner as in Comparative Example 1, except that the temperature of the vessel during the precipitation treatment and during the introduction of transport ammonia gas was maintained at 1125°C. Pipe 20 was omitted, and ammonia gas was introduced from pipe 10 at a rate of 1000 ml / min for a 6-hour heat treatment. Physical properties were measured, revealing no vaporization or precipitation. Consequently, the average particle size was large, impurities were high, and the desired product could not be obtained. The physical properties of the resulting gallium nitride particles are shown in Tables 2 and 3.

[0088] Comparative Example 3

[0089] Gallium oxide treatment was performed in the same manner as in Examples 1 to 3, except that precipitation treatment was not performed. Since precipitation treatment was not performed, gallium nitride particles were obtained, but the average particle size was small, the oxygen content was high, and the purity was low, failing to obtain the desired product. The physical properties of the obtained gallium nitride particles are shown in Tables 2 and 3.

[0090] [Table 1]

[0091] Production conditions in the precipitation process

[0092] [Table 2]

[0093] Physical properties of recovered GaN particles

[0094] [Table 3]

[0095] Impurity content in recycled GaN particles

[0096]

[0097] The elements measured are Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd.

[0098] Description of Reference Numerals

[0099] 1 Heating furnace

[0100] 2 Gallium oxide filling container

[0101] 3. Container for recovering deposited gallium nitride particles

[0102] 10 piping

[0103] 20 piping

[0104] While the present invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the present invention.

[0105] It should be noted that this application is based on Japanese Patent Application (Japanese Patent Application No. 2019-184480) filed on October 7, 2019, the entirety of which is incorporated herein by reference. In addition, all references cited herein are incorporated as their entirety.

Claims

1. A gallium nitride particle, characterized in that: The oxygen content is less than 0.5 atomic%, the total impurity amount of Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is less than 10wtppm, and the bulk density is 1.2g / cm 3 The gallium nitride particles have a primary particle size of 50% or more and a primary particle size of 50% or less of 5 μm and 50 μm or less.

2. The gallium nitride particle according to claim 1, characterized in that The total impurity amount of Mg and Si is less than 5 wtppm.

3. The gallium nitride particle according to claim 1 or 2, characterized in that The Si impurity content is less than 1 wtppm.

4. The gallium nitride particle according to claim 1 or 2, characterized in that The oxygen content is 0.1 atomic % or less.

5. The gallium nitride particle according to claim 1 or 2, characterized in that The average particle size of the gallium nitride particles is less than 20 μm.

6. The gallium nitride particle according to claim 1 or 2, characterized in that The method is obtained as follows: after gallium oxide is used as a starting material for nitriding treatment, as a precipitation treatment, transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the nitrided gallium oxide heated to 1150°C to 1300°C for 3 hours to 30 hours, and precipitation ammonia gas heated to 1000°C to 1100°C is introduced into the vaporized gallium nitride for 3 hours to 30 hours to precipitate the gasified gallium nitride, thereby obtaining gallium nitride particles.

7. A method for producing gallium nitride particles according to any one of claims 1 to 5, characterized in that: After gallium oxide is used as a starting material for nitriding treatment, as a precipitation treatment, transport ammonia gas heated to a temperature of 1150°C to 1300°C is introduced into the nitrided gallium oxide heated to 1150°C to 1300°C for 3 to 30 hours. With respect to the vaporized gallium nitride, precipitation ammonia gas heated to 1000°C to 1100°C is introduced for 3 to 30 hours to precipitate the vaporized gallium nitride, thereby obtaining gallium nitride particles. 8 . A sintered body comprising the gallium nitride particles according to claim 1 . 9 . A sputtering target, comprising the sintered body according to claim 8 . 10 . A thin film formed using the sputtering target according to claim 9 .

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